Re: Draft for basic NUMA observability

On Fri, Mar 14, 2025 at 1:08 PM Bertrand Drouvot
<bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
> On Fri, Mar 14, 2025 at 11:05:28AM +0100, Jakub Wartak wrote:
> > On Thu, Mar 13, 2025 at 3:15 PM Bertrand Drouvot
> > <bertranddrouvot(dot)pg(at)gmail(dot)com> wrote:
> >
> > Hi,
> >
> > Thank you very much for the review! I'm answering to both reviews in
> > one go and the results is attached v12, seems it all should be solved
> > now:
>
> Thanks for v12!
>
> I'll review 0001 and 0003 later, but want to share what I've done for 0002.
>
> I did prepare a patch file (attached as .txt to not disturb the cfbot) to apply
> on top of v11 0002 (I just rebased it a bit so that it now applies on top of
> v12 0002).

Hey Bertrand,

all LGTM (good ideas), so here's v13 attached with applied all of that
(rebased, tested). BTW: I'm sending to make cfbot as it still tried to
apply that .patch (on my side it .patch, not .txt)

> === 9
>
> -static bool firstUseInBackend = true;
> +static bool firstNumaTouch = true;
>
> Looks better to me but still not 100% convinced by the name.

IMHO, Yes, it looks much better.

> === 10
>
> static BufferCachePagesContext *
> -pg_buffercache_init_entries(FuncCallContext *funcctx, PG_FUNCTION_ARGS)
> +pg_buffercache_init_entries(FuncCallContext *funcctx, FunctionCallInfo fcinfo)
>
> as PG_FUNCTION_ARGS is usually used for fmgr-compatible function and there is
> a lof of examples in the code that make use of "FunctionCallInfo" for non
> fmgr-compatible function.

Cool, thanks.

> and also:
>
> === 11
>
> I don't like the fact that we iterate 2 times over NBuffers in
> pg_buffercache_numa_pages().
>
> But I'm having having hard time finding a better approach given the fact that
> pg_numa_query_pages() needs all the pointers "prepared" before it can be called...
>
> Those 2 loops are probably the best approach, unless someone has a better idea.

IMHO, it doesn't hurt and I've also not been able to think of any better idea.

> === 12
>
> Upthread you asked "Can you please take a look again on this, is this up to the
> project standards?"
>
> Was the question about using pg_buffercache_numa_prepare_ptrs() as an inlined wrapper?

Yes, this was for an earlier doubt regarding question "19" about
reviewing the code after removal of `query_numa` variable. This is the
same code for 2 loops, IMHO it is good now.

> What do you think? The comments, doc and code changes are just proposals and are
> fully open to discussion.

They are great, thank You!

-J.